The present invention relates to a device for locking a suture in vivo, more particularly to a device for locking a suture in vivo without the need for tying knots once the suture is placed within tissue. The present invention also relates to a method for using such a device to approximate tissue and to lock the suture in place.
It is known in the art to approximate damaged or torn tissue by use of a suture. In many instances, the suture is looped through tissue, and the two ends are then secured together. Prior art methods for securing a suture include tying knots. Other methods include providing a filament having various protruding portions and securing the filament against one of those protruding portions. See, e.g., U.S. Pat. No. 5,520,691, incorporated herein by reference. Still other prior art methods include compressing the suture between a cylinder/piston wall interface. See, e.g., U.S. Pat. No. 5,630,824, incorporated herein by reference. Such sutures may be used to approximate damage in soft tissue or to attach soft tissue to bone.
The present invention provides a suture locking device that relies on frictional forces. In one embodiment, a suture is passed through an anchor having a tapered or stepped cannula. The suture is then passed through tissue, may be passed through or around a second anchor located on the opposite side of the defect, and looped back through the cannula. One end of the suture may be provided with a knot or bead. As the surgeon pulls on the second end, the knot or bead enters the cannula, pulls the two anchors toward each other, then both strands wedge tightly in the cannula. In an alternative embodiment, instead of a knot or bead, a slip knot is provided on the first end. The second end may be threaded through the slip knot. Again, as the surgeon pulls on the second end, the knot will enter the tapered or stepped cannula, pull the two anchors together, and wedge both strands tightly within the cannula.
In another embodiment of this invention, a locking ring is used to secure the sutures to the anchor. The anchor may be provided with a split section and the suture would pass through this split section. The locking ring may be of either the push-type or the pull-type, and when engaged, the locking ring would force the portions of the split section together, thus wedging the split section together and locking the suture strands in place. The split section may be provided with teeth to grip the suture better.
In another embodiment, the suture may be secured with a snap groove provided on the anchor. As with the locking ring arrangement, the anchor would be provided with a split section. A tooth on one section is sized and shaped to mate with a groove on the other section. When the tooth is snapped into the groove, the suture strands would be locked into place.
An additional embodiment may employ a wedge design. In such a design, the anchor may be provided with a cylindrical cannula, and a wedge would be provided to fit tightly within the cannula. The wedge itself may be partially cannulated to aid in insertion, but the suture would also, in part, pass along the exterior of the wedge, so that frictional forces would secure the suture between the wedge and the inside of the cannula, in order to lock the suture in place.
Alternatively, the suture locking device may comprise laminated sheets. Slits in the laminated sheets would allow the suture to pass in one direction with little resistance. However, the sheets would be designed to lock on the suture when the suture is pulled in the reverse direction. Thus, the surgeon could pull on the suture to tighten it, and the suture would remain locked in place.
Some embodiments of the present invention are described for situations in which the suture is looped through tissue, and two ends of the suture must be secured. Other embodiments are described in which each end of the suture strand is secured independently. It will be understood that the invention may be employed in situations involving a single strand or with multiple suture or filament strands. Also, it will be understood that the scope of this invention is not limited specifically to securing two ends of a suture within one locking mechanism.
The anchor may be made of biocompatible material such as stainless steel, titanium, cobalt chrome, and polyethylene. Preferably, biodegradable materials may also be used, including poly lactic acid and poly lactic-glycolic acid. Other biodegradable materials are known. See, e.g., U.S. Pat. No. 4,976,715, hereby incorporated by reference. The suture may be made of resorbable or non-resorbable material, as are known in the art.
Therefore, in one embodiment of the present invention, a device is provided for locking a suture in place, the device comprising an anchor having a cannula, the cannula for receiving a suture, and a locking mechanism for locking the suture in place. The locking mechanism may comprise a bead, knot, or wedge sized to wedge within the cannula or the locking mechanism may comprise a locking ring. The cannula may be cylindrical, tapered, or stepped.
In another embodiment of the present invention, a device is provided for locking a suture in place, the device comprising an anchor having a cannula and a locking mechanism. The cannula is for receiving the suture, and the locking mechanism is for locking the suture within the cannula. The locking mechanism may comprise a locking ring or a snap groove.
In still another embodiment of the present invention, a device for locking a suture in place is provided, comprising an anchor having a front edge and a rear edge, the anchor having a cannula extending from the front section to the rear section, and a locking mechanism. In this embodiment, the suture comprises a first end and a second end, the suture extending through the cannula of the anchor from the rear edge to the front edge, through a portion of tissue, and extending back through the cannula from the front edge to the rear edge, the second end protruding from the rear edge of the suture. The locking mechanism comprises a bead located at the first end of the suture, and the bead sized to fit snugly within a portion of the cannula. Pulling the second end of the suture causes the bead to travel toward the front edge of the anchor and to wedge within the portion of the cannula, thereby locking the suture in place.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.